Time relay



` 30 electromagnet,

Ptented Nov. 2, 192,6.

WILHELM HENN'IlG rnrERsN, or GAMLA ALLMANNA SVENSKA ELEKTBISKA AIKTIEBOLAGET, OF VASTEBAS, SWEIDEN, 'A'

'CORPORATION or swnmiN.

' Application fliea November 4, 1924, serial no Timev relays 'based on'the thermic principle, that is, in which the heat produced a resistance member by the traversing cur-` rent is stored up ina body and after in- 5 creasing the temperature -of said body, up to a certain limit, in some way ca'uses' ainovement leading to release,.are often considered as appropriate especially for -the protection of small loadl objects, as, separate motors or heating elements. This is. for'the reason, that such relays are -adapted for copying, V more or less truly, the temperature fluctuations of the load object, and can `thus be readily adjusted to release even at th/e instant whenlthere is realdanger. The release is generally efected either by' thefusion of the` resistance member or of an adjacent jpart, which is rather unsuitable, as it necessitates the insertion of spare parts, or by deformations caused by the heat, -which however are comparatively Asmall and slow and therefore must be combined withl a specialmechanism with, 'Springs or electromagnets for the r'elef` n`g movement.l In this'way a comparativ complicated system of` movable parts'is obtained which may easily get in disorder.

The present invention relates to a time relay comprisin a heatingmember and an ut having a minimum of movable parts and 'therefore bein extremely simple and reliable. The c aracteristic feature of the invention is that the heating member itself or a part in close connection therewith forms pait of the magnetic circuit and consists of a material which is ferromagnetic at ordinary temperature but becomes only feebly magnetic at a comparatively low rise of temperature, so

40 that it will act 'as a Large air-gap in the magnetic circuit and reduce the attraction on an armature sufliciently to permit it to be.pulled away from the magnet and effect release., The rest of the magnetic circuit preferably is composed mainly of iron, and the heating member forming part thereof may lie immediately adj acent to the air-'gap between the fixed `portion of the circuit and the armature, which is generally .to be pre- 'ferred, or in other place.

Iron and alloys With a comparatively great percentage of iron generally ldo not lose their ferromagnetic properties until a rather ,high temperature (red heat) is suitable.

POSTEN, LUDVIKA, SWEDEN, ASSIGNOR T0 :'rmn Barier.

. 747,`852,'a'nd in Sweden December 10, 1923.

` tain alloys. Pure nickel loses entirely its ferromagneticproperties at about 300 C.,

and its natural alloy with copper, so-calledl Monel meta-l (containing about Ni and 1/3 Cu) already 'at about 9094100 C. 'By alloying nickel 'with copper in other proportions,1nearly any value of the critical temperature below 300 may be obtained. In w some' cases the relation between the ermeability' and the temperature follows rather a straight line, in others the former sinks more rapidly at a certain Critical value of: the latter. Both forms maybe employed, but the last-mentioned one is generally more Another type of alloys which have fe'rromagnetic properties at ordinary temperature but lose these at a' comparatively low rise of temperature, are the so-ca-lled Heusler alloys, consisting of aluminium and,l manganese with or without an addition of copper. p w

A preferred form of; the invention is shown in the accompanying'drawing in a side view in Fig. 1 and in a plan view (with certain parts taken away) in Fig. 2.

v1 is an electromagnet having a .threelegged core, in the, middle leg of which the armature 2 is rotatably mounted so as to occupy different positions, depending upon whether the attraction from one outer leg or the other is the Stronger one. Normally the armature is assumed to be'more stronglyl attracted by the leftL leg so as to be kept in the position shown in the drawing, Be-

tweenA the iron core pro er of this leg and the .armature there is, owever, inserted Aa piece 3 of a nickel-copper alloy or the like which is heated by the influence'of the eurrent. vIn the form shown this is eflected thereby, that the piece 3 which is slotted in zig-zag, is traversed by the secondary current from a current transformerg'tlre core of which is formed by thelelectromagnet '1, and the primary winding by the coil 4 of t e latter. The secondary winding is/a coil 5 on the same core, having few turns When' the current in the coil 4, thus also uv the resistance member' 3, is increased above a certain value, the temperature in said member rises so' much that its permeability sinks substantially below its normal value. The magnetic induction is therefore forced over in the other leg of the magnet, and finally the attraction thereof will predominate, so that the armature is thrown over and operates 'a movable contact 6 which. it presses againstl a stationary one 7, or performs any other suitable releasing movement. The arrangement may be such, that the releasing motion does not takeV place until the membel1 3 has practically lost its ferromagnetic properties, or such that release occurs already when its permeability has been substantially reduced.

The adjustment of the relay for different intensities of current or for diflerent releasing time limits can be efected in a known manner, in part by connecting a` greater or smaller portion of the primary magnet ,coil 4 in circuit by means of a series of taps 8 in part by a screw 9 regulating the normal value of the air gaps at the two ends of the a-rmature. A spring 10 keepsthe armature in its normal position when there is no current on the relay. i

'Having thus dcscribed my inv'ention and the manner of its operation, I declare that what I claim is In electric relays, a three-legged iron core7 a Win-ding on the' middle leg thereof, an armature pivoted in said midtlle leg, means for holding said armature normally in such position as to make the attractivc f`l force of one outer leg Stronger than that. of the other, a body losing its perineability at low temperature in the first of said outcr legs, and means for electrically heating said body to suflicient temperature to reduce substantially its permeability.

In testimony whereof I have signed my name to this specification.

VVILHELM HENNING PETERSN 

